Rowdy94

iTrader: (13)

I'm going to be putting 3.73 gears in my 2.73 car, as well as changing everything in the PCM. My question is this...

Do I simply need to change the gear ratio in that section? Will I need to scale the shift point charts as well, or will tunercat do that automatically when I enter the new ratio?

I would also imagine that I will have to do something to the trans. tables to get lockup and everything correct.

Could somebody go over each table or section that needs to be modified after a gear swap?

koolaid_kid

iTrader: (21)

After a gear swap, no other tables should need to be changed.
It is when you change the stall that you must start fooling with those other tables.

Rowdy94

iTrader: (13)

The shift points are all in the tables as MPH values. Will those automatically be scaled and adjusted when the new ratio is entered?

EDIT: Hell, I guess I can get on the software and see for myself.

Rowdy94

iTrader: (13)

I just toyed with it a bit. The shift point MPHs do not change when the new ratio is entered. At WOT, the table shows 48 MPH for the 1-2 shift. When I have 3.73s, it'll need to be much lower. Apparently those tables will need to be scaled down.

Rhino

iTrader: (6)

I just watched a guy tune in a new set of gears using tunercat this weekend. While I don't know all tables that he touched, there were a significant amount. I know for a fact that he modified the shift points and lockup.

koolaid_kid

iTrader: (21)

In LT1Edit (not that it is the same for you, since you did not say what software you were using) there are two tables. One is rpm. One is mph. Depending on which it is listening to, it will shift according to that table.

moehorsepower

iTrader: (3)

Well this is not entirely true, The shift points consist of BOTH RPM and MPH, there is a threshold where either or must be within a certain percent of each other or else you will bang off the rev limiter...At times maybe you can only adjust possibly one parameter, but usually you need to adjust both...

Rowdy94

iTrader: (13)

That's what I figured. The shift points should be easy, as the entire table can be scaled by an amount. I just flat out don't know at this point what to play with for lockup.

Rhino

iTrader: (6)

It seems that he scaled the lockup as well, although I didn't get a good look at it due to his laptop getting low on battery and needing to finish up quick. I'll shoot him an email today and see if he can explain what he was doing.

Rowdy94

iTrader: (13)

That would be really awesome if you could get that info. I'm thinking it will be pretty simple though when I actually get around to needing to do it.

2xLS1

iTrader: (25)

2.73/3.73 = .7319034
Scale every shift table, WOT (norrmal, hot, cold kickdown) and part throttle (normal, performance, manual, cruise) , and every TCC table (normal, manual, hot, performance, cruise) by that amount.

Rowdy94

iTrader: (13)

Outstanding. That's kind of the thoughts that I had, I just didn't want to do anything without confirmation. Thanks a lot.

aknovaman

iTrader: (7)

Yes, you need to scale all the trans tables, if you are using Tunercat after setting up the speedo settings. I manually generate the values and then adjust them based upon my GPS readings. The trans will shift based upon engine rpm AND vehicle speed.

BTW, I was the guy at the Kansas City Camaro Nat's this past weekend, tuning the LS2 '69 Convertible Camaro. The previous "Professional Tuner" did not scale ANY of the trans tables for the 3.5 gears. He used a 4.1 gear file and it was a mess.
Respectfully,
Anthony